Migration from 3.x.x to 4.0.0

[pb82]

Description

Changes required to release 4.0.0, and make it work via OLM. This should also contain the migration guide from 3.x.x to 4.0.0.

CRDs are upgraded to v1 (from v1alpha1).

TODO

1. Automatically upgrade CRs to v1 (see https://kubernetes.io/docs/tasks/extend-kubernetes/custom-resources/custom-resource-definition-versioning/#upgrade-existing-objects-to-a-new-stored-version)
2. Finish migration documentation

Verification steps

1. Install 3.10.3 via OLM
2. Deploy Grafana and some Dashboards
3. Uninstall 3.10.3 via OLM
4. Apply the CatalogSource (provided below)
5. Install 4.0.0
6. Verify that all imported Dashboards are still present.

The following CatalogSource can be used to install 4.0.0 via OLM:

apiVersion: operators.coreos.com/v1alpha1
kind: CatalogSource
metadata:
  name: grafana-operator-manifests
  namespace: grafana
spec:
  sourceType: grpc
  image: quay.io/grafana-operator/controller-index:v4.0.0

[pb82]

Yes, sorry. I had to make changes to those files and I think they should be in the repo.

[hubeadmin]

/lgtm

@pb82 Are you going to do TODO's in this PR as well?

Tried verifying but CRC keeps crashing :| I'll retry again tomorrow

[NissesSenap]

Great work as always @pb82!
Found a few things that I'm wondering about.

Except the files already changed I think we should remove grafana-operator v3 specific stuff like:
https://github.com/grafana-operator/grafana-operator/blob/master/deploy/operator.yaml
Or if not remove at least rename the folder to v3 or legacy to naturally point people to V4.

Or do we want to use those files for deployment in the future as well? Would could write a small shell script that generates the files using kustomize build command.

Depending on what we choose here we need to update the docs as well.

[NissesSenap]

Upgrade documentation thoughts:

[pb82]

@NissesSenap @HubertStefanski all feedback addressed, are you ok to merge this?

[NissesSenap]

LGTM
Great job and perfect timing with the new 1.22 release 🥇